A few questions regarding oil-pressure, incl. gauges...

[uberswede]

First off, I just spent almost an hour searching and reading posts that seemed to be CLOSE to what I wanted, but none with exactly what I'm looking for.

To start, I've got a 1997 Talon, and we just finished swapping in a 1g from a '90 or a '91. I'm almost positive it was from a '91, but I could be wrong. Will that make a difference?


Anyways, one of the last things I did before we fired up the motor was install an AEM Digital Oil Pressure gauge. We tapped the sensor into the same 1/8th-inch hole that the original factory sender was in. The reason we took that out is because the factory gauge isn't working at all. The last owner of the car put in those white-gauge faces and kinda screwed up a few of the gauges in the process.

Now, first problem is that there seems to be an oil leak from where we tapped in, or right around it. Initially, we had trouble getting the AEM sensor in the factory location, despite reading everywhere that both are "standard 1/8th-inch"... The factory sender, however, seems to have slightly tapered threads, and the AEM sensor doesn't... but we still got it in there.

I've got the car back at the shop that did a lot of the motor work (including mounting the AEM sensor for me while they had it in the air) and they seem adamant that the AEM sensor is the problem, and that's why it's leaking. The fit seemed super tight, and there was even thread locker on it, and then some sealant around the edge of it after it was in. Still, it's leaking from somewhere.

Could it be from the oil pump bolts? Maybe missing a gasket behind the pump? We don't know yet, but there does seem to be some kind of adapter between the pump and the block. Is that factory as well?


On top of all of this, my oil pressure readings seem to be all over the place. I've seen as low as 10psi at idle, then it's gone easily over 100 a few times... I don't know how MUCH higher, as the gauge is only 0-100psi. Had I known 0-150 was available when I ordered the gauge, I would have ordered that instead.

Anyways, can anybody shed any light on any of this? It would be much appreciated.

 

[greekgodchaos]

To start, I've got a 1997 Talon, and we just finished swapping in a 1g from a '90 or a '91.

A 1g what exactly?

 

[Absit]

Now, first problem is that there seems to be an oil leak from where we tapped in, or right around it. Initially, we had trouble getting the AEM sensor in the factory location, despite reading everywhere that both are "standard 1/8th-inch"... The factory sender, however, seems to have slightly tapered threads, and the AEM sensor doesn't... but we still got it in there.

It is standard, in England. 1/8 BSPT, not 1/8 NPT. Reading any thread about it on this site would have told you that.

On top of all of this, my oil pressure readings seem to be all over the place. I've seen as low as 10psi at idle, then it's gone easily over 100 a few times... I don't know how MUCH higher, as the gauge is only 0-100psi. Had I known 0-150 was available when I ordered the gauge, I would have ordered that instead.

If you're leaking at the sensor it seems logical the sensor would show some errors. 10 PSI at idle is possible. Over 100 at WOT is also possible, especially without balance shafts and proper porting.

 

[uberswede]

greekgodchaos : a 1g 4g63t awd. ECI Multi... umm... not sure what else you'd want to know from that.

Absit : So basically, I'm looking at threading metric into standard, or vice versa? Which is BSPT and which is NPT? Will I need some kind of adapter then, or what?

I'll keep an eye on the PSI, and maybe think about swapping the 0-100psi for a 0-150psi. The leak there is VERY minimal, barely a drip, but enough that I don't like it. And yes, the balance shafts have been eliminated, but I don't believe any porting has been done. What would you suggest? I remember reading something about porting a hole on the back of the oil pump, and then something on the head?

 

[jimbob_843]

Yeah its pretty much just re threading the hole. Idk which one i cant remember. I just bought the little autometer kit and it had everything i needed.

 

[uberswede]

Well, is it even possible for me to use this sensor where I'm using it then? I've got AEM on the phone saying it will work, and I've at the shop telling me to return the AEM product saying it's the problem, it's leaking, and it's the wrong threading.

So now I'm just standing here like an idiot not knowing what to do.

 

[Absit]

The port in the OFH is BSPT (it's not metric, it's still 1/8",) you can buy a NPT > BSPT adapter from Autometer or various other sources assuming you haven't damaged the threads in the OFH.

 

[uberswede]

Well, the shop I brought the car back to because of the oil leak ended up cracking the oil filter housing. LUCKILY, I still had one kicking around from another parts motor, but even still... what a piss off.

Here's the kicker... they still insist that I DON'T need a BSP-to-NPT adapter.... they insist that the AEM sensor is the same thread as the Mitsu sensor, and that there will be no problem...

I DID, however, find an adapter at a hydraulics store.... but playing around with the threads, etc.... both the AEM and OEM sensor both thread into the adapter without a problem... so, I am actually finding it harder to believe that the sensor is the wrong size... such a small ridiculous problem holding me up. I haven't driven this car since July 15th last year, ARGH!!

I want my DSM back

 

[miguelmcv]

both the AEM and OEM sensor both thread into the adapter without a problem...



Yes they both will thread in. BUT..... One has only one thread less then the other one. and that's what makes the difference.
Check that close and you will see that one will fit better then the other one.
One will be a little loose then the other one.

You can install it just like that. But you have to put some thread Sealer, and you (have to leave it for 2 to 4 Hours) Before starting the car.
You have to leave the Sealer to dry completely and you will have no leak after that.

I did mine like that with out a single leak.

 

[uberswede]

Well, the shop ended up cracking the oil filter housing while working with the sensors, trying to figure out and fix the oil leak there. Luckily, I had another sitting on a backup motor. Had it cleaned up and serviced; good to go.

Picked up an adapter for the slight difference in threads; good to go there as well.

Everything was perfect until I took it for a run up the highway... Something else went. Dunno yet. Cue me starting a whole new thread.

 

[99gst_racer]

There's a very small difference between NPT and BSPT threads. For future reference, you can run a tap through the port on the filter housing to re-cut the threads to better fit NPT threads. It's a quick and simple fix and better than using an adapter IMO.


How was your oil pressure after you fixed the leak?

 

[uberswede]

Oil pressure now seems normal, from my understanding... anywhere between 10-30 at idle, depending on temp... and I don't see it go over 100 really, then again I haven't been driving it hard yet since it's a freshly built motor... I'm considering popping the oil filter housing off and opening up that one port I saw others doing to illeviate a bit of excess pressure... Especially since there aren't any balance shafts in the motor anymore.